Establishment And Application Evaluation Of A Combined Immunoassay Method Based On A Stable Isotope Tagging Strategy And Inductively Coupled Plasma Mass Spectrometry For Detecting Human Chorionic Gonadotropin

Inductively coupled plasma mass spectrometry(ICP-MS)is an elemental analysis tool with high sensitivity and multi-component analysis capabilities.A novel method characterized by the usage of immunoreaction coupled to a stable isotope tagging strategy and an ICP-MS system was firstly proposed in 2001.In this method,antibodies were labeled with rare earth elements(REEs)or their stable isotopes,followed by direct detection using ICP-MS to indirectly determine the relevant antigens concentration.Compared with the traditional methods,the matrix effect of biological samples has little effect on ICP-MS detection.The detection is not affected by the optical,electrical,electrochemical,and magnetic properties of the labels and has good stability and high sensitivity.Since more than 130 stable isotopes can be sensitively detected by ICP-MS at the same time,the ICP-MS immunoassay technology also has good multi-component detection potential,and has been proven to be used for the detection of small molecules proteins,nucleic acids,single cells and a range of biological samples at al.However,there have been few reports of its application in clinical testing.Human chorionic gonadotropin(HCG)is a glycoprotein secreted by syncytiotrophoblast cells.HCG is not only an important indicator for judging early pregnancy but is also closely related to the development of many tumors.Therefore,we chose HCG as the research object to establish an immunoassay method based on ICP-MS for the quantitative detection of HCG.The experimental conditions for the immunoassay were optimized.Then according to Clinical and Laboratory Standards Institute(CLSI)guidelines,the analytical performance was evaluated,including standard curve,the limit of detection(LOD),the upper limit of quantification(ULo Q),linearity,precision,accuracy,specificity,stability,and interference test(hemoglobin,Bilirubin,triglycerides).After that,130 clinical samples were collected and analyzed by the proposed method.The results were compared with the results measured by Electrochemical immunoassay(ECLIA).The results showed that the LOB of the assay was 0.29 m IU/m L and the ULo Q was 11300 m IU/m L.Good linearity in the range of 1.16～8365.62m IU/m L,and the correlation coefficient of linearity was higher than 0.995(R~2=0.9980).The obtained recoveries ranged from 97.53%to 102.01%,while the intra-assay imprecision of high value samples,and low value samples,were 2.97%and 6.08%,respectively;The inter-assay imprecision of high value samples,and low value samples,were 3.98%and 7.08%,respectively.And there was no significant cross-reaction with Luteinizing hormone(LH),follicular stimulating hormone(FSH),and thyroid-stimulating hormone(TSH).Interference test results deviated by less than±10%in the presence of hemoglobin≤2g/L,bilirubin≤274?mol/L,triglycerides≤37 mmol/L.Compared with the commercial ECLIA method for clinical sample detection,the proposed method showed a significant correlation(R~2=0.9770)and statifying agreement.The combination of ICP-MS and a stable element labeling based immunoassay for HCG detection was established successfully and the general performance of this system was acceptable,thus indicating that the assay has potential for the clinical application.